The invention relates to an improved compressed-gas switch having two switching parts which are movable relative to one another.
A switch of this general type is known for instance from German Offenlegungsschrift No. 2,930,839. In this switch, the minimum flow cross-section of the inner inlet duct is not only considerably smaller than that of the outer inlet duct but, in addition, the inner inlet duct is also connected to a space in which the quenching gas has a significantly higher pressure during a switching-off process than in the space connected to the outer inlet duct. The quenching gas blowing onto the arc during the switching-off process, therefore, has a much higher velocity in the region of the outlet opening from the inner inlet duct than in the region of the outlet opening from the outer inlet duct. The root of the switching arc is driven by the quenching gas component with the high outlet velocity into the hollow burn-off contact of the first switching part and in conjunction with the quenching gas component with the lower outlet velocity a turbulence is produced in the arc gases thus resulting at the quenching of the arc. When short-circuit currents in the terminals are being quenched, however, it is possible that difficulties will occur since the switching path has not yet been optimally dielectrically restabilized after the quenching of the switching arc before the returning voltage appears.
The invention has an object of further developing the generic switch in such a manner that short-circuit currents at a distance and those at the terminals can be switched off with high reliability.
This object and others are achieved by the switch according to the invention. The switch is distinguished by the fact that the nozzle of insulating material can be greatly stressed thermally and dielectrically at its surface facing the switching path and that simultaneously in the switching path the pressure of the quenching gas is distributed in a manner optimum for controlling the returning voltage in the case of short-circuits at a distance and at the terminals.